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<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>
  <script>
    let arrAges = [15, 19, 21, 33, 18, 24, 10]
    let sum = 0
    for (let i = 0; i < arrAges.length; i++) {
      sum += arrAges[i]
    }
    console.log(`班级里同学们平均年龄为${sum / arrAges.length}`)
  </script>
</body>
</html>